For many years, acrolein (C.sub.3 H.sub.4 O) has been produced by controlled oxidation of propylene (C.sub.3 H.sub.6) in the presence of suitable catalysts. Examples of such catalysts and methods for making them are disclosed in British Patents Nos. 963,610 and 1,146,870; French Patent No. 1,447,982; and in the Japanese reference C. Z. Xing and H. Inoue, Kagaku Kogaku Ronbunshu, Vol. 10, No. 4, pp. 439-45 (1984).
Acrolein has many important uses, including treatment of waste water or water used to pressurize oil and gas fields, where the addition of only 6-10 parts per million (ppm) of acrolein controls the growth of microbes in feedlines to prevent plugging. Acrolein also scavenges hydrogen sulfide (H.sub.2 S) from aqueous solutions to reduce corrosion. Acrolein can also be used to make other products, e.g., glycerine, allyl alcohol, glycidol, glutaraldehyde, and propanol.
The biological activity of acrolein also prevents growth of organisms in liquid fuels, such as jet fuel, and controls the growth of algae, aquatic weeds, mollusks, and the like, in irrigation and process water systems. Slime formation is a serious problem in paper manufacturing, but is controlled by the use of only 0.4-0.6 ppm acrolein as a slimicide.
Acrolein has been made commercially for more than 40 years by the catalytic air oxidation of propylene using large fixed-bed reactors and fluidized bed reactors which require large manufacturing sites and high capital expenditures. The resulting crude acrolein undergoes expensive purification, which results in commercial grade (96%) acrolein. This concentrated acrolein is then packaged, transported, repackaged, and distributed to the end-user's facility. The concentrated acrolein is usually stored for long periods (often several months to a few years) before it is actually used. This procedure increases the possibility of accidental spills and premature reaction due to excessive handling, transportation and storage.
In prior art procedures using acrolein to treat irrigation or process water, liquid fuel, or the like, the commercial grade acrolein is purchased in bulk, and thereafter added to the liquid to be treated in an amount to give the desired concentration of acrolein. Properly performed, this procedure usually gives good results, but it is subject to the inherent hazards arising from the instability of concentrated acrolein. In the absence of a suitable inhibitor, acrolein rapidly polymerizes in the presence of light or heat to form a highly crosslinked solid of little or no use. Accordingly, concentrated acrolein requires an inhibitor, such as hydroquinone, to prevent that reaction.
Even though appropriate procedures for handling concentrated acrolein are well known, unwanted reactions occur, resulting not only in the loss of the acrolein, but sometimes the storage and handling equipment as well.
The hazards of handling, shipping, and storing concentrated acrolein could be reduced by diluting it, say, with water. However, storage of dilute acrolein usually results in the degradation of the material over time. In the case of water, hydrolysis ensues, producing hydrolysis products that have little or no biocidal or hydrogen sulfide scavenging performance. Maximum levels of acrolein dissolved in water are about 19-25%, depending on temperature. After a few days, these levels diminish to only a few percent. U.S. Pat. Nos. 4,215,147 and 4,215,148 describe the use of systems at low pH to extend the life of acrolein in water. Unfortunately, after several weeks to a few months, the level of acrolein decreases to low, unusable levels.
Because of its hazardous nature, acrolein is not generally used in offshore oil production platforms. Furthermore, increasing concerns of accidents during transportation on public highways and use in areas of high-density populations significantly retard the use of acrolein, and are beginning to reduce its usage, because a chemical accident could cause disastrous consequences.